Disabling DTS cuts off sound

I don´t get the whole codec thing - it´s horribly confusing and I´m really trying to understand, but there´s still a bunch of theory I probably misunderstood.
However I have a little problem with my setup and I can´t get movies containing DTS tracks to work. The ATV 4 is connected to my TV which includes a “Dolby Digital Plus” decoder - I suppose this means DTS is not natively supported? The thing is that my AV-Receiver (DAV-DZ330), which is connected through an ARC port to my TV, shows “DTS” whenever I use a DTS track and it works - for 5 minutes and then some weird robotic sounds appear unless I reset the receiver. So I disabled the DTS HDMI function in Infuse and then there´s no sound at all.
What do I have to do in order to get this whole thing to work? I´ve tried a bunch of things: That includes changing the “digital output format” at my TV from “PCM” to “Compressed”, changing all the sound options in Infuse and even those within the tvOS settings. I´d like to avoid buying new hardware but it seems I´ll have to buy a complete new AV-Receiver including a new surround system …